Since the 1970s, fiber optics have been used to transmit data. Fiber optics are well suited to transmit large amounts of data because many different data streams can be transmitted along a single fiber-optic waveguide by multiplexing the data streams. One example of multiplexing is wavelength-division multiplexing. In wavelength-division multiplexing, many different data streams, each using a separate wavelength, are transmitted through a single waveguide.